Pictures Reproduced

Pictures Reproduced

From the mechanical point of view, there are three ways to apply ink to paper so as to reproduce a picture. These are intaglio printing, relief or letterpress printing, and planographic printing.

In an intaglio plate, the lines to be printed are cut below the surface, making troughs and hollows. The ink roller deposits ink in the depressed portions; the surface is wiped clean; paper is laid over it, and when the plate is inverted the ink settles upon the paper. You can often detect intaglio printing from the fact that the ink tends to bulge somewhat over the surface of the paper. The process is often used for calling cards, fine art prints, and the like, but is too costly for long press runs.

A letterpress cut ("cut" is the general term for the plate used in printing a picture) is so-called because the lines to be printed are raised in relief over the surface, just as letters and characters of type are raised in relief. The ink roller deposits in only on the raised portions.

The so-called planographic plate is flat, but owing to its composition the ink roller deposits ink only on the portions that represent lines to be printed.